The present invention relates to a new and improved construction of apparatus or installation for processing waste paper.
Generally speaking, the waste paper processing apparatus of the present development is of the type comprising a stock pulper equipped with a housing containing therein a rotor and a sieve or screen plate located at the region of the rotor. The sieve plate is provided with openings through which the liquid stock suspension, formed during pulping and slushing of the waste paper, is removed for further treatment and processing at a papermaking machine.
An installation of this type is disclosed, by way of example, in German Pat. No. 2,757,580. With this prior art waste paper processing installation, the stock suspension, obtained by defiberizing the waste paper, is withdrawn through the sieve or screen plate and, following removal of heavy rejects or contaminants, is infed to a secondary stock pulper. In this secondary stock pulper, containing a rotor movable about a sieve, there is further refined the stock suspension, whereupon the good stock is withdrawn through the sieve for further treatment and use. In the secondary pulper there are removed and separated light rejects or contaminants, such as for instance plastic parts and plastic foils, by means of a special outlet leading from the center of a vortex core of the secondary pulper.
The heretofore installation is afflicted with the drawback that the light rejects, such as the aforementioned plastic foils, prior to their separation are comminuted relatively intensely. This, in turn, constitutes an unuseful expenditure in both time and energy. Also, there exists the danger of clogging the relatively small openings or holes of the sieve or screen plate of the stock pulper.